Spring element for use in an apparatus for attaching to a semiconductor and a method for making

ABSTRACT

A spring element used in a temporary package for testing semiconductors is provided. The spring element is compressed so as to press the semiconductor, either in the form of a bare semiconductor die or as part of a package, against an interconnect structure. The spring element is configured so that it provides sufficient pressure to keep the contacts on the semiconductor in electrical contact with the interconnect structure. Material is added and/or removed from the spring element so that it has the desired modulus of elasticity. The shape of the spring element may also be varied to change the modulus of elasticity, the spring constant, and the force transfer capabilities of the spring element.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a divisional application of co-pending application Ser.No. 09/009,169 filed on Jan. 20, 1998 by David R. Hembree et al.,entitled A SPRING ELEMENT FOR USE IN AN APPARATUS FOR ATTACHING TO ASEMICONDUCTOR AND A METHOD OF MAKING. This is application is furtherrelated to co-pending application Ser. No. 09/678,562, which is also adivisional of application Ser. No. 09/009,169.

BACKGROUND OF THE INVENTION

[0002] The present invention relates in general to spring elements, and,more particularly, to a spring element for use in an apparatus forattaching to a plurality of contacts of a semiconductor.

[0003] Unpackaged or bare semiconductor dies are used to constructmulti-chip modules (MCMs) and other electronic devices. Unpackaged diesmust be tested and burned in during the manufacturing process to certifyeach die as a known good die. This has led to the development oftemporary packages that hold a single bare die for testing and burn-in.The temporary packages provide the electrical interconnection betweenthe test pads on the die and external test circuitry. Exemplarytemporary packages are disclosed in U.S. Pat. Nos. 5,302,891, 5,408,190and 5,495,179 to Wood et al., which are herein incorporated byreference.

[0004] Typically, this type of temporary package includes aninterconnect having contact members that make a temporary electricalconnection with the test pads on the die. The temporary package can alsoinclude an attachment device that presses the die against theinterconnect. The attachment device may include a clamping device thatattaches to a package base and a spring element that presses the dieagainst the interconnect. The configuration of the spring element isdependent on a number of factors. The spring element must be able towithstand relatively high compressive forces and relatively high burn-intemperatures without experiencing compression set. Further, thedimensions of the spring element must be such that it is compatible withthe temporary package. Finally, the spring element must be able towithstand the amount of pressure required for pressing the die againstthe interconnect without causing an excessive amount of force to betransferred to the die, and thus damaging the same.

[0005] Accordingly, there is a need for a spring element which iscompatible with the temporary packages and environment used to test andburn-in semiconductor. Preferably, such a spring element would bereusable and inexpensive to manufacture.

SUMMARY OF THE INVENTION

[0006] The present invention meets this need by providing a springelement having a modulus of elasticity which may be adjusted accordingto the required environment. Material may be removed from or added tothe spring element to change the modulus of elasticity as needed. Theshape of the spring element may also be varied to change the modulus ofelasticity, the spring constant, and the force transfer capabilities ofthe spring element.

[0007] According to a first aspect of the present invention, a springelement comprises a first elastic member comprised of a firstelastomeric material having a first modulus of elasticity. The firstelastic member has a plurality of holes formed therein such that thespring element has an overall modulus of elasticity different from thefirst modulus of elasticity. The spring element may further comprise asecond elastic member comprised of a second elastomeric material havinga second modulus of elasticity. The second elastic member is positionedin at least one of the plurality of holes formed in the first elasticmember such that the overall modulus of elasticity is different from thefirst and second moduli of elasticity. The spring element may furthercomprise a plurality of the second elastic members positioned in aplurality of the plurality of holes in the first elastic member. Thefirst and second elastomeric materials may comprise silicone.

[0008] According to another aspect of the present invention, a springelement comprises a first elastic member comprised of silicone having afirst modulus of elasticity and a plurality of second elastic memberseach comprised of silicone having a second modulus of elasticity. Theplurality of second elastic members are positioned in each of aplurality of holes in the first elastic member such that the springelement has an overall modulus of elasticity different from the firstand second moduli of elasticity.

[0009] According to yet another aspect of the present invention, aspring element comprises a first elastic member and a second elasticmember. The first elastic member is comprised of a first elastomericmaterial having a first modulus of elasticity and the second elasticmember is comprised of a second elastomeric material having a secondmodulus of elasticity. The second elastic member is positioned withinthe first elastic member such that the spring element has an overallmodulus of elasticity different from the first and second moduli ofelasticity. The spring element may further comprise a plurality of thesecond elastic members positioned within the first elastic member. Thesecond elastic member may be substantially spherical or elongated. Thefirst elastomeric material may comprise foam-like silicone while thesecond elastomeric material may comprise substantially solid silicone.

[0010] According to another aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding a first elastic member comprised of a first elastomericmaterial having a first modulus of elasticity. A portion of the firstelastomeric material is removed from the first elastic member such thatthe spring element has an overall modulus of elasticity different fromthe first modulus of elasticity.

[0011] According to a further aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding a first elastic member comprised of a first elastomericmaterial having a first modulus of elasticity. The first elastic memberhas a plurality of holes formed therein such that the spring element hasan overall modulus of elasticity different from the first modulus ofelasticity. The semiconductor may comprise a semiconductor die or asemiconductor die formed within a semiconductor package. Thesemiconductor package may comprise a package selected from the groupconsisting of a chip-scale package, a ball grid array, a chip-on-board,a direct chip attach, and a flip-chip.

[0012] According to a still further aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding a first elastic member comprised of silicone having a firstmodulus of elasticity and a plurality of second elastic members eachcomprised of silicone having a second modulus of elasticity. The firstelastic member includes a plurality of holes formed therein with each ofthe plurality of holes receiving one of the plurality of second elasticmembers such that the spring element has an overall modulus ofelasticity different from the first and second moduli of elasticity.

[0013] According to a yet still further aspect of the present invention,an apparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding an elastic member comprised of an elastomeric material havinga modulus of elasticity. A hole is formed in the elastic member suchthat the spring element has an overall modulus of elasticity differentfrom the modulus of elasticity of the elastomeric material. The elasticmember is also shaped so as to engage an outer edge of the semiconductorsuch that a force applied by the attachment device as the interconnectstructure is pressed against the semiconductor is substantially uniformaround the semiconductor. The elastic member may be o-ring shaped andcomprised of silicone.

[0014] According to another aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding a first elastic member and a second elastic member. The firstelastic member comprises a first elastomeric material having a firstmodulus of elasticity and the second elastic member comprises a secondelastomeric material having a second modulus of elasticity. The secondelastic member is positioned within the first elastic member such thatthe spring element has an overall modulus of elasticity different fromthe first and second moduli of elasticity.

[0015] According to yet another aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementcomprised of a plurality of interwoven threads. The plurality ofinterwoven threads may comprise silicone.

[0016] According to a further aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding an elastic member comprised of an elastomeric material havinga modulus of elasticity. At least one cavity is formed in the elasticmember such that the spring element has an overall modulus of elasticitydifferent from the modulus of elasticity of the elastomeric material.The elastic member may have a plurality of cavities formed therein. Theelastomeric material may be substantially solid.

[0017] According to a still further aspect of the present invention, anapparatus for attaching to a plurality of contacts of a semiconductorcomprises an interconnect structure comprising a plurality of conductorspatterned to match corresponding ones of the plurality of contacts onthe semiconductor and an attachment device pressing the interconnectstructure against the semiconductor to provide an electrical connectionbetween the plurality of conductors and the corresponding ones of theplurality of contacts. The attachment device comprises a spring elementincluding an elastic member having a variable spring constant. Theelastic member may have a triangular or diamond shaped cross-section.The elastic member may have a repeating triangular or diamond shapedcross-section.

[0018] According to another aspect of the present invention, a method ofmaking a spring element comprises providing a first elastic membercomprised of a first elastomeric material having a first modulus ofelasticity. A plurality of holes are formed in the first elastic memberto adjust an overall modulus of elasticity of the spring element. Themethod may further comprise the step of adding a second elastic membercomprised of a second elastomeric material having a second modulus ofelasticity to one of the plurality of holes so that the overall modulusof elasticity is different from the first and second moduli ofelasticity. The method may further comprise the step of adding aplurality of the second elastic members to a plurality of the pluralityof holes in the first elastic member. The plurality of holes may beformed by punching, laser drilling or molding the first elastic member.

[0019] According to yet another aspect of the present invention, amethod of making a spring element comprises providing a first elasticmember comprised of a first elastomeric material having a first modulusof elasticity. A plurality of holes are wet drilled in the first elasticmember to adjust an overall modulus of elasticity of the spring element.

[0020] According to a further aspect of the present invention, a methodof making a spring element comprises providing a first elastic membercomprised of a first elastomeric material having a first modulus ofelasticity. A plurality of holes are wet drilled in the first elasticmember to adjust an overall modulus of elasticity of the spring element.One of a plurality of second elastic members are then added to each ofthe plurality of holes. Each of the plurality of second elastic membersis comprised of a second elastomeric material having a second modulus ofelasticity such that an overall modulus of elasticity of the springelement is different from the first and second moduli of elasticity.

[0021] According to a still further aspect of the present invention, amethod of making a spring element comprises providing a first elasticmember comprised of a first elastomeric material having a first modulusof elasticity. A second elastic member composed of a second elastomericmaterial having a second modulus of elasticity is formed in the firstelastic member such that the spring element has an overall modulus ofelasticity different from the first and second moduli of elasticity. Themethod may further comprise the step of forming a plurality of thesecond elastic members within the first elastic member.

[0022] Accordingly, it is an object of the present invention to providea spring element which is compatible with the temporary packages andenvironment used to test and burn-in semiconductors. It is anotherobject of the present invention to provide a spring element which isreusable and inexpensive to manufacture. Other features and advantagesof the invention will be apparent from the following description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is an exploded view of a temporary package for testingsemiconductors;

[0024]FIG. 2 is a cross-sectional view of the assembled temporarypackage shown in FIG. 1;

[0025]FIG. 3 is a plan view of an interconnect structure for testingsemiconductor dies used in the temporary package of Fig.1 according tofirst aspect of the present invention;

[0026]FIG. 4 is a schematic plan view of a semiconductor die to betested in the temporary package of FIG. 1 according to the first aspectof the present invention;

[0027]FIG. 5 is a schematic plan view of a semiconductor package to betested in the temporary package of FIG. 1 according to a second aspectof the present invention;

[0028]FIG. 6 is a plan view of an interconnect structure for testingsemiconductor packages used in the temporary package of Fig.1 accordingto the second aspect of the present invention;

[0029]FIG. 7 is a perspective view of a spring element according to afirst embodiment of the present invention;

[0030]FIG. 8 is perspective view of a spring element according to asecond embodiment of the present invention;

[0031]FIG. 9 is perspective view of a spring element according to athird embodiment of the present invention;

[0032]FIG. 10 is perspective view of a spring element according to afourth embodiment of the present invention;

[0033]FIG. 11 is perspective view of a spring element according to afifth embodiment of the present invention; and

[0034]FIG. 12 is perspective view of a spring element according to asixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Referring now to FIGS. 1 and 2, a typical temporary package 10used for testing a semiconductor 12 is shown. The temporary package 10includes a package base 14, an interconnect structure 16, and anattachment device 18. The interconnect structure 16 establisheselectrical communication between the package base 14 and thesemiconductor 12. The attachment device 18 secures the semiconductor 12to the package base 14 and presses the semiconductor 12 against theinterconnect structure 16. The attachment device 18 includes a pressureplate 20, a spring element 22, a cover 24 and a pair of clips 26, 28.

[0036] The interconnect structure 16 is positioned within a recess 30formed within the package base 14. The semiconductor 12 is positionedover the interconnect structure 16 and held within another recess 32formed within the package base 14. The spring element 22 is secured tothe cover 24 using an appropriate adhesive. However, it will beappreciated by those skilled in the art that the spring element 22 mayused without being secured to the cover 24. The pressure plate 20overlies the semiconductor 12 and is pressed against the semiconductor12 by the spring element 22 and the cover 24. Accordingly, thesemiconductor 12 is pressed against the interconnect structure 16thereby establishing an electrical connection between the semiconductor12, the interconnect structure 16 and the package base 14.

[0037] The cover 24 is secured to package base 14 by the clips 26, 28.The clips 26, 28 engage a top portion of the cover 24 and are secured tothe package base 14 through corresponding openings 34, 36 in the packagebase 14. It will be appreciated by those skilled in the art that othertypes of latching mechanisms may be used to secure the cover 24 to thepackage base 14. The cover 24, the spring element 22, the pressure plate20 and the package base 14 each include a central opening which aredesignated 24A, 22A, 20A and 14A, respectively. The openings 24A, 22A,20A and 14A are used during assembly of the package 10 to permit thesemiconductor 12 to be held by a vacuum tool (not shown) during opticalalignment of the semiconductor 12 and the interconnect structure 16. Thevacuum tool may also be used to disassemble the temporary package 10 asrequired.

[0038] The temporary package 10 may be used to test semiconductors 12 ina variety of forms. According to a first aspect of the presentinvention, the temporary package 10 is used to test bare semiconductordies 12′, see FIG. 4. The interconnect structure 16 is arranged so as tointerface with such semiconductor dies 12′. Referring to FIG. 3, theinterconnect structure 16 includes a plurality of conductors 38. Each ofthe plurality of conductors 38 includes a contact member 40, aconnection line 42 and a bonding site 44. The contact members 40 areformed in a pattern which correspond to a plurality of contacts or bondpads 46 on the semiconductor die 12′; see also FIG. 4. The contactmembers 40 are adapted to contact and establish an electrical connectionwith the bond pads 46 on the semiconductor die 12′. For example, thecontact members 40 may include a raised portion (not shown) whichcontacts the bond pads 46 as the semiconductor die 12′ is pressedagainst the interconnect structure 16. The connection lines 42 terminateat the bonding sites 44 for connection to the package base 14. Thebonding sites are connected to respective conductive traces 48 on thepackage base 14 using bond wires 50. The interconnect structure 16 mayinclude a number of test structures (not shown) for evaluating variouselectrical characteristics of the interconnect structure 16. Onceassembled, the semiconductor die 12′ may be tested and burned-in asdesired.

[0039] In the illustrated embodiment, the interconnect 16 is formed of asilicon substrate using conventional semiconductor technology.Similarly, the plurality of conductors 38 are formed of an appropriateconductive material using conventional semiconductor technology. Theinterconnect structure 16 may be formed according to U.S. Pat. Nos.5,326,428; 5,419,807 and 5,483,741 which are herein incorporated byreference. In the illustrated embodiment, the semiconductor die 12′ isformed of a silicon substrate with a number of additional semiconductorlayers forming the desired semiconductor device using conventionalsemiconductor technology. It will be appreciated by those skilled in theart that the semiconductor die 12′ may be formed of other semiconductormaterials, such as gallium arsenide.

[0040] According to a second aspect of the present invention, thetemporary package 10 is used to test semiconductor packages 12″; seeFIG. 5. The semiconductor package 12″ includes at least onesemiconductor die 12′ and an additional structure 52. The structure 52basically reroutes the bond pads 46 from the edge of the semiconductordie 12′ towards the center of the semiconductor die 12′. This reroutingreduces the precision required for aligning the bond pads 46 with thecontact members 40 as there is a greater area in which to position thebond pads 46. The structure 52 includes a plurality of conductive traces54 electrically coupled to respective bond pads 46. The traces 54 arerouted toward the center of the semiconductor die 12′ in any desiredpattern. The end of each trace 54 includes bonding member 56, such asolder ball. The bonding member 56 is typically larger than thecorresponding bond pad 46 such that the precision in aligning thecontact members 40 with the bonding member 56 is reduced. Thesemiconductor package 12″ may comprise a chip-scale package (CSP), ballgrid array (BGA), chip-on-board (COB), direct chip attach (DCA),flip-chips and other similar packages. As shown in FIG. 6, theinterconnect structure 16 is arranged and configured to interface withthe semiconductor package 12″ as is known in the art. It should beapparent from the above description that the semiconductor 12 maycomprise bare semiconductor dies 12′ and semiconductor dies arranged inpackages, such as semiconductor packages 12″ as is known in the art.

[0041] The spring element 22 is composed of an elastomeric material. Inthe illustrated embodiment, the elastomeric material comprises siliconeas it is compatible with the high temperatures associated with burn-in.However, silicone and the silicon used to form the semiconductor 12 tendto bond together due to surface attraction and the compressive forcesencountered as the semiconductor 12 is pressed against the interconnectstructure 16. Such a bond could damage the underlying structures of thesemiconductor 12 as well as the semiconductor 12 itself as thesemiconductor 12 and the spring element 22 are separated. The pressureplate 20 acts as an interface between the semiconductor 12 and thespring element 22 to prevent such a bond from forming. The pressureplate 20 is thus composed of a suitable material which is compatiblewith the spring element 22 and the semiconductor 12 so as to prevent abond from forming between any of the aforementioned structures. It willbe appreciated by those skilled in the art that spring element 22 may becomposed of other elastomeric materials, such as appropriate urethanesand polyesters. Further, the pressure plate 20 may be omitted if thematerial used to form the spring element 22 does not bond to thesemiconductor 12 when subjected to high pressure and temperature.

[0042] Typically, the semiconductor 12 and the temporary package 10 arerelatively small thereby limiting the area or thickness of the springelement 22. The thickness of the spring element 22 may range betweenapproximately 15 mils (0.381 mm) to approximately 125 mils (3.177 mm).However, it will be appreciated by those skilled in the art that thespring element 22 may be any desired thickness depending on theparticular package 10 and semiconductor 12. The spring element 22absorbs some of the force or pressure applied to it as it is compressedby the cover 24. The spring element 22 is sized and configured totransfer a desired amount of pressure to the semiconductor 12. Asufficient amount of pressure needs be applied to the semiconductor 12so that it properly engages the interconnect structure 16. However, anexcessive amount of pressure could damage the semiconductor 12 and theinterconnect structure 16. As the dimensions of the spring element 22are limited due to the size of the semiconductor 12 and the package 10,the configuration of the spring element 22 may be changed so that itexhibits the desired pressure absorption and force transfercharacteristics.

[0043] The force applied by the spring element 22 may be changed bychanging the area of the spring element 22 to be compressed. Forexample, a pressure plate 20 which is larger than the outer dimensionsof the semiconductor 12 may be used with a lower psi spring element 22.The larger pressure plate 20 limits the overall compression height ofthe spring element 22 while applying the appropriate amount of force.Reducing the amount that the spring element 22 is compressed lessens thecompression set of the spring element 22.

[0044] One feature of the spring element 22 which may be changed is itsmodulus of elasticity. Lowering the modulus of elasticity of the springelement 22 would enable it to absorb more force or pressure so that theamount of pressure applied to the semiconductor 12 is within acceptablelevels. Another way of describing such function is forming low psi (lbs.per square inch) materials from high psi materials. Conversely, themodulus of elasticity may be increased so as to lessen the amount offorce or pressure absorbed by the spring element 22 and thus increasethe amount of force or pressure applied to the semiconductor 12.

[0045] Referring now to FIG. 7, the spring element 22 according to afirst embodiment of the present invention is shown. The spring element22 comprises a first elastic member 100 comprised of a first elastomericmaterial having a first modulus of elasticity. In the illustratedembodiment, the first elastomeric material comprises silicone. Thesilicone may be substantially solid or foam-like by having gas bubblesblown through it during fabrication using conventional methods. Itshould be apparent that the first modulus of elasticity is dependent, inpart, on the configuration of the silicone as being foam-like orsubstantially solid. Foam-like material is more easily compressed thansubstantially solid material as the gas bubbles in the foam-likematerial are more easily compressible. A plurality of openings 102 areformed in the first elastic member 100 in addition to the opening 22Adescribed above. The plurality of openings 102 may extend partially orcompletely through the first elastic member 100. The plurality ofopenings 102 are formed by wet drilling the first elastic member 100.Wet drilling is particularly advantageous as it will not leave residualoil or particles from the silicone on the first elastic member 100. Theplurality of openings 102 may also be formed using other appropriatemethods, such as by molding, regular drilling, laser drilling or bypunching out the desired openings. An overall modulus of elasticity ofthe spring element 22 is thus dependent on the size and total number ofopenings 102 through the first elastic member 100. The overall modulusof elasticity of the spring element 22 is lower than the first modulusof elasticity of the first elastic member 100 in direct relation to thequantity of first elastomeric material removed from the first elasticmember 100. The spring element 22 is thus more compressible.

[0046] The overall modulus of elasticity of the spring element 22 may befurther changed by adding one or more second elastic members 104 to thefirst elastic member 100. The second elastic members 104 are comprisedof a second elastomeric material having a second modulus of elasticitydifferent from the first modulus of elasticity. The second elasticmembers 104 may be positioned in one or more of the openings 102 asdesired. In the illustrated embodiment, the second elastic members 104also comprise silicone which may be substantially solid or foam-like.The overall modulus of elasticity of the spring element 22 with thesecond elastic members 104 in the openings 102 will be at least greaterthan the overall modulus of elasticity of the spring element 22 withempty openings 102. Further, the overall modulus of elasticity of thespring element 22 may be greater than the first modulus of elasticity ifthe second elastomeric material is stiffer or more dense than the firstelastomeric material.

[0047] Referring now to FIG. 8, the spring element 22 according to asecond embodiment of the present invention is shown, with like referencenumerals corresponding to like elements. In this embodiment, one or moreof the second elastic members 104 are positioned within the firstelastic member 100. The second elastic members 104 are formed with thefirst elastic member 100 as the first elastic member 100 is fabricated.As with the first embodiment, the overall modulus of elasticity isdependent on the number and size of the second elastic members 104. Thesecond elastic members 104 may have any desired shape. In theillustrated embodiment, the second elastic members 104 are generallyspherical or oblong. The second elastic members 104 may be foam-like orsubstantially solid depending on the desired properties of the springelement 22.

[0048] Referring now to FIG. 9, the spring element 22 according to athird embodiment of the present invention is shown. The spring element22 comprises an elastic member 106 comprised of an elastomeric materialhaving a modulus of elasticity. The elastic member 106 is shaped so thatit engages an outer edge of the semiconductor 12 as it presses thesemiconductor 12 against the interconnect structure 16. The springelement 22 of this embodiment includes a relatively large hole 108through the elastomeric material such that the overall modulus ofelasticity of the spring element 22 is different from the modulus ofelasticity of the elastic member 106. As the spring element 22 engagesthe outer edge of the semiconductor 12, the force or pressure from thecompressed spring element 22 is substantially uniform around thesemiconductor 12. By engaging only the outer edge of the semiconductor12, the applied force or pressure from the spring element 22 issubstantially uniform compared to a sheet in which more force orpressure is applied to the center than the edges. In the illustratedembodiment, the elastic member 106 is o-ring shaped.

[0049] Referring now to FIG. 10, the spring element 22 according to afourth embodiment of the present invention is shown. The spring element22 comprises a plurality of interwoven threads 110. The amount in whichthe spring element of the fourth embodiment may be compressed isdependent, in part, to the size and the degree in which the threads 110are woven together. The threads 110 are comprised of an elastomericmaterial which is silicone in the illustrated embodiment.

[0050] Referring now to FIG. 11, the spring element 22 according to afifth embodiment of the present invention is shown. The spring element22 comprises an elastic member 112 comprised of an elastomeric materialhaving a modulus of elasticity. One or more cavities or dimples 114 areformed in the elastic member 112. The overall modulus of elasticity ofthe spring element 22 is thus dependent on the size and number ofcavities 114. The cavities 114 may be formed by molding them into theelastic member 112 or by cutting cavities out of the elastic member 112.The cavities 114 may comprise any desired shape.

[0051] Referring now to FIG. 12, the spring element 22 according to asixth embodiment of the present invention is shown. The spring element22 comprises an elastic member 116 having a variable spring constant.The elastic member 116 has a repeating diamond shaped cross-section witha set of first peaks 116A and a set of second peaks 116B. The springconstant of the elastic member 116 changes based on the level ofcompression. The spring constant increases in direct proportion to thelevel of compression. The spring constant increases with compressionbecause a greater amount of material is compressed. As there is lessmaterial near the peaks 116A, 116B, the amount of material compressed isless such that the spring constant is low. However, as compressionincreases, the amount of material compressed also increases such thatthe spring constant is higher. The elastic member 116 may have differentshapes provided that the spring constant changes with the degree ofcompression. The elastic member 116 may have a triangular cross-sectionor a repeating triangular shaped cross-section. The elastic member 116may be formed by molding or extruding an appropriate elastomericmaterial. The elastomeric material may be substantially solid orfoam-like.

[0052] It will be appreciated by those skilled in the art that thespring element 22 may have any combination of the above embodiments. Thefinal configuration of the spring element 22 will be dependent on thedesired physical properties of the spring element 22 as well as thedimensional limitations for each particular package 10 and semiconductor12. It will be further appreciated by those skilled in the art that thespring element 22 may be used with other temporary packages.

[0053] Having described the invention in detail and by reference topreferred embodiments thereof, it will be apparent that modificationsand variations are possible without departing from the scope of theinvention defined in the appended claims.

1. A spring element for a temporary package comprising: a first elasticmember comprised of a first elastomeric material having first forcetransfer characteristics, said first elastic member having a pluralityof holes formed therein such that said spring element has overall forcetransfer characteristics different from said first force transfercharacteristics, wherein said spring is configured to be insertablebetween a cover and a package base of said temporary package and isarranged so as to transfer a predetermined amount of force as saidspring element is compressed within said temporary package by saidcover.
 2. The spring element of claim 1, further comprising a secondelastic member comprised of a second elastomeric material having secondforce transfer characteristics, said second elastic member positioned inat least one of said plurality of holes formed in said first elasticmember such that said overall force transfer characteristics of saidfirst and second elastic members is different from said first and secondforce transfer characteristics.
 3. The spring element of claim 2,wherein said second elastomeric material comprises silicone.
 4. Thespring element of claim 1, wherein said first elastomeric materialcomprises silicone.
 5. The spring element of claim 1, further comprisinga plurality of second elastic members, each of said plurality of secondelastic members comprised of a second elastomeric material having secondforce transfer characteristics, each of said plurality of second elasticmembers positioned in at least one of said plurality of holes formed insaid first elastic member such that said overall force transfercharacteristics of said first and second elastic members is differentfrom said first and second force transfer characteristics.
 6. A springelement for a temporary package comprising: a first elastic member beingcomprised of silicone having first force transfer characteristics, saidfirst elastic member having a plurality of holes formed therein; and aplurality of second elastic members each being comprised of silicone andhaving second force transfer characteristics, each of said plurality ofsecond elastic members positioned in at least one of said plurality ofholes in said first elastic member such that said spring element hasoverall force transfer characteristics different from said first andsecond force transfer characteristics, wherein said spring element isconfigured to be insertable between a cover and a package base of saidtemporary package and is arranged so as to transfer a predeterminedamount of force as said spring element is compressed within saidtemporary package by said cover.
 7. A spring element for a temporarypackage comprising: a first elastic member comprised of a firstelastomeric material having first force transfer characteristics; and, asecond elastic member comprised of a second elastomeric material havingsecond force transfer characteristics, said second elastic memberpositioned within said first elastic member such that said springelement has overall force transfer characteristics different from saidfirst and second force transfer characteristics, wherein said springelement is configured to be insertable between a cover and a packagebase of said temporary package and is arranged so as to transfer apredetermined amount of force as said spring element is compressedwithin said temporary package by said cover.
 8. The spring element ofclaim 7, further comprising a plurality of said second elastic memberspositioned within said first elastic member.
 9. The spring element ofclaim 7, wherein said second elastic member is substantially spherical.10. The spring element of claim 7, wherein said second elastic member iselongated.
 11. The spring element of claim 7, wherein said firstelastomeric material comprises silicone.
 12. The spring element of claim7, wherein said first elastomeric material comprises foam-like material.13. The spring element of claim 7, wherein said second elastomericmaterial comprises silicone.
 14. The spring element of claim 13, whereinsaid silicone is substantially solid.
 15. A spring element for atemporary package comprising: a first elastic member comprised of afirst elastomeric material having a cross-section defined by at leastone peak, wherein said elastic member exhibits a variable springconstant that changes with a degree of compression of said at least onepeak, wherein said spring element is configured to be insertable betweena cover and a package base of said temporary package and is arranged soas to transfer a predetermined amount of force as said spring element iscompressed within said temporary package by said cover.
 16. The springelement of claim 15, wherein said elastic member has a triangular shapedcross-section.
 17. The spring element of claim 15, wherein said elasticmember has a repeating triangular shaped cross-section.
 18. The springelement of claim 15, wherein said elastic member has a diamond shapedcross-section.
 19. The spring element of claim 15, wherein said elasticmember has a repeating diamond shaped cross-section.
 20. A springelement for a temporary package comprising: elastomeric materialarranged as a plurality of interwoven threads, wherein said springelement is configured to be insertable between a cover and a packagebase of said temporary package and is arranged so as to transfer apredetermined amount of force as said spring element is compressedwithin said temporary package by said cover.
 21. The spring element ofclaim 20, wherein said plurality of interwoven threads comprisesilicone.
 22. An apparatus for attaching to a plurality of contacts of asemiconductor, said apparatus comprising: an interconnect structurecomprising a plurality of conductors patterned to match correspondingones of said plurality of contacts of said semiconductor; and anattachment device for pressing said interconnect structure against saidsemiconductor to provide an electrical connection between said pluralityof conductors and said corresponding ones of said plurality of contacts,said attachment device comprising a spring element including a firstelastic member and a second elastic member, said first elastic membercomprising a first elastomeric material having first force transfercharacteristics and said second elastic member comprising a secondelastomeric material having second force transfer characteristics, saidsecond elastic member being positioned within said first elastic membersuch that said spring element has overall force transfer characteristicsdifferent from said first and second force transfer characteristics. 23.The apparatus of claim 22, further comprising a plurality of said secondelastic members formed within said first elastic member.
 24. Theapparatus of claim 22, wherein said second elastic member issubstantially spherical.
 25. The apparatus of claim 22, wherein saidsecond elastic member is elongated.
 26. The apparatus of claim 22,wherein said first elastomeric material comprises silicone.
 27. Theapparatus of claim 22, where said first elastomeric material comprisessilicone foam.
 28. The apparatus of claim 22, wherein said secondelastomeric material comprises silicone.
 29. The apparatus of claim 28,wherein said silicone is substantially solid.
 30. An apparatus forattaching to a plurality of contacts of a semiconductor, said apparatuscomprising: an interconnect structure comprising a plurality ofconductors patterned to match corresponding ones of said plurality ofcontacts on said semiconductor; and an attachment device pressing saidinterconnect structure against said semiconductor to provide anelectrical connection between said plurality of conductors and saidcorresponding ones of said plurality of contacts, said attachment devicecomprising a spring element comprised of a plurality of interwoventhreads.
 31. The apparatus of claim 30, wherein said plurality ofinterwoven threads comprise silicone.
 32. An apparatus for attaching toa plurality of contacts of a semiconductor, said apparatus comprising:an interconnect structure comprising a plurality of conductors patternedto match corresponding ones of said plurality of contacts of saidsemiconductor; and an attachment device for pressing said interconnectstructure against said semiconductor to provide an electrical connectionbetween said plurality of conductors and said corresponding ones of saidplurality of contacts, said attachment device comprising a springelement including an elastic member comprised of an elastomeric materialhaving force transfer characteristics, said elastic member having atleast one cavity formed therein such that said spring element hasoverall force transfer characteristics different from said forcetransfer characteristics of said elastomeric material.
 33. The apparatusof claim 32, wherein said elastic member has a plurality of cavitiesformed therein.
 34. The apparatus of claim 32, wherein said elastomericmaterial is substantially solid.
 35. A method of making a spring elementfor a temporary package comprising: providing a first elastic membercomprised of a first elastomeric material having first force transfercharacteristics; sizing said spring element so as to be insertablebetween a cover and a package base of a temporary package; and, forminga plurality of holes in said first elastic member to adjust overallforce transfer characteristics of said spring element, wherein said thequantity and size of said plurality of holes is selected such that saidspring element transfers a predetermined amount of force as said springelement is compressed within said temporary package.
 36. The method ofclaim 35, further comprising adding a second elastic member comprised ofa second elastomeric material having second force transfercharacteristics to one of said plurality of holes, said overall forcetransfer characteristics being different from said first and secondforce transfer characteristics.
 37. The method of claim 36, furthercomprising adding a plurality of said second elastic members to aplurality of said plurality of holes in said first elastic member. 38.The method of claim 35, wherein said first elastic member comprisessilicone.
 39. The method of claim 35, wherein forming a plurality ofholes in said first elastic member to adjust overall force transfercharacteristics of said spring element comprises punching said pluralityof holes in said first elastic member.
 40. The method of claim 35,wherein forming a plurality of holes in said first elastic member toadjust overall force transfer characteristics of said spring elementcomprises laser drilling said plurality of holes in said first elasticmember.
 41. The method of claim 35, wherein forming a plurality of holesin said first elastic member to adjust overall force transfercharacteristics of said spring element comprises molding said pluralityof holes in said first elastic member.
 42. The method of claim 35,wherein said plurality of holes penetrate less than a thickness of saidfirst elastomeric material defining cavities therein.
 43. The method ofclaim 35, wherein at least a portion of said plurality of holes arethrough holes.
 44. A method of making a spring element comprising:providing a first elastic member comprised of a first elastomericmaterial having first force transfer characteristics; sizing said springelement so as to be insertable between a cover and a package base of atemporary package; wet drilling a plurality of holes in said firstelastic member to adjust overall force transfer characteristics of saidspring element; and, adding at least one second elastic member to aselect one of said plurality of holes, each second elastic member beingcomprised of a second elastomeric material having second force transfercharacteristics such that overall force transfer characteristics of saidspring element are different from said first and second force transfercharacteristics, wherein said the quantity and size of said plurality ofholes, and the quantity of said at least one second elastic member isselected such that said spring element transfers a predetermined amountof force as said spring element is compressed within said temporarypackage.
 45. A method of making a spring element comprising: providing afirst elastic member comprised of a first elastomeric material havingfirst force transfer characteristics; sizing said spring element so asto be insertable between a cover and a package base of a temporarypackage; forming at least one second elastic member composed of a secondelastomeric material having second force transfer characteristics insaid first elastic member such that said spring element has overallforce transfer characteristics different from said first and secondforce transfer characteristics, wherein said the quantity and size ofsaid second elastic members is selected such that said spring elementtransfers a predetermined amount of force as said spring element iscompressed within said temporary package.
 46. The method of claim 46,further comprising the step of forming a plurality of said secondelastic members within said first elastic member.
 47. The method ofclaim 45, wherein said second elastic member is substantially spherical.48. The method of claim 45, wherein said second elastic member iselongated.
 49. The method of claim 45, wherein said first elastomericmaterial comprises silicone.
 50. The method of claim 45, wherein saidfirst elastomeric material comprises foam-like material.
 51. The methodof claim 45, wherein said second elastomeric material comprisessilicone.
 52. The method of claim 45, wherein said silicone issubstantially solid.